Method and structure for thin film photovoltaic cell using similar material junction

Abstract

A method for forming a thin film photovoltaic device. The method provides a transparent substrate including a surface region. A first electrode layer overlies the surface region. A copper layer is formed overlying the first electrode layer and an indium layer is formed overlying the copper layer to form a multi-layered structure. At least the multi-layered structure is subjected to a thermal treatment process in an environment containing a sulfur bearing species to forming a bulk copper indium disulfide. The bulk copper indium disulfide material has a surface region characterized by a copper poor surface region having a copper to indium atomic ratio of less than about 0.95:1 and n-type impurity characteristics. The bulk copper indium disulfide material excluding the copper poor surface region forms an absorber region and the copper poor surface region forms at least a portion of a window region for the thin film photovoltaic device. The method optionally forms a high resistivity transparent material having an intrinsic semiconductor characteristic overlying the copper poor surface region. A second electrode layer overlies the high resistivity transparent layer.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application No. 61 / 116,625, filed Nov. 20, 2008, entitled “METHOD AND STRUCTURE FOR THIN FILM PHOTOVOLTAIC CELL USING SIMILAR MATERIAL JUNCTION” by inventor Howard W. H. Lee, commonly assigned and incorporated by reference herein for all purposes.BACKGROUND OF THE INVENTION[0002]The present invention relates generally to photovoltaic materials and manufacturing method. More particularly, the present invention provides a method and structure for manufacture of thin film photovoltaic cells. Merely by way of example, the present method and materials include absorber materials made of copper indium disulfide species, copper tin sulfide, iron disulfide, or others for single junction cells or multi junction cells.[0003]From the beginning of time, mankind has been challenged to find way of harnessing energy. Energy comes in the forms such as petrochemical, hydroelectric, nuclear, wind,...

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Benefits of technology

[0008]In a specific embodiment, a method for forming a thin film photovoltaic device is provided. The method includes providing a transparent substrate including a surface region. A first electrode layer is formed overlying the surface region. The method includes forming a copper layer overlying the first electrode layer and forming an indium layer overlying the copper layer to form a multi-layered structure. In a specific embodiment, the method includes subjecting at least the multi-layered structure to a thermal treatment process in an environment containing sulfur bearing species and forming a bulk copper indium disulfide material from at least the treatment process of the multi-layered structure. In a specific embodiment, the method forms a bulk copper indium disulfide material from at least the treatment process of the multi-layered structure. The bulk copper indium disulfide material having a surface region characterized by a copper poor surface region comprising a copper to indium atomic ratio of less than about 0.95:1. In a specific embodiment, the copper poor surface region has n-type impurity characteristics. In a specific embodiment, the bulk copper indium disulfide material excluding the copper poor surface region forms an absorber region and the copper poor surface region forming at least a portion of a window region for the photovoltaic cell. In a specific embodiment, the method includes forming a high resistivity transparent material overlying the copper poor surface region having the n-type impurity characteristics. The high resistivity transparent layer uses a semiconductor material having an intrinsic semiconductor characteristic in a specific embodiment. A second electrode layer is formed overlying the high resistivity transparent layer.

[0009]In an alternative embodiment, a thin film photovoltaic device is provided. The thin film photovoltaic device includes a substrate comprising a surface region. The thin film photovoltaic device includes a first electrode layer overlying the surface region. A chalcopyrite material including a chalcopyrite material surface region overlies the first electrode layer. In a specific embodiment, the chalcopyrite material includes a copper indium disulfide material and a copper poor copper indium disulfide surface region. The copper poor copper indium disulfide surface region has an atomic ratio of Cu:In of about 0.99 and less and has an n type impurity characteristics. In a specific embodiment, the copper poor copper indium disulfide surface region provides for a window layer for the photovoltaic device. The thin film photovoltaic device also includes a second electrode layer overlying the window layer.

[0010]In a yet alternative embodiment, a thin film photovoltaic device is provided. The thin film photovoltaic device includes a substrate including a surface region. A firs...

Problems solved by technology

Unfortunately, the supply of petrochemical fuel is limited and essentially fixed based upon the amount available on the planet Earth.

Additionally, as more people use petroleum products in growing amounts, it is rapidly becoming a scarce resource, which will eventually become depleted over time.

Although solar energy is environmentally clean and has been successful to a point, many limitations remain to be resolved before it becomes widely used throughout the world.

However, crystalline mate...

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